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Monday, May 26, 2014

Post WPX

The radio performed very nicely. I spent some time trying to figure out how to optimize this radio for contesting.

My conclusion for antennas is that you need some kind of multi-band antenna to maximize the features of this radio. My F5K had 2 entire RF paths for each receiver. In other words I had discrete single band antennas and amplifiers connected to ANT 1 and ANT 2 on that radio. Each amp had its own TX key as well. I had one band following amp (ALS-1300) and one antenna switch which could both be driven by BCD using band data from the radio. I also had some other discrete antennas so I could set up ANT 2 as the run antenna, and use ANT 1 for band hopping. It worked well.

For this radio since there are not discrete receivers (SCU's) a single multi-band contest antenna would likely work best.

This is my eznec design of a "contest vertical". This antenna uses a single 34.5 ft tapered aluminum tube and covers 40, 20, 15, 10. It uses no tuners, coils or switching and should be good for many KW, all off one coax. Here is the SWR graph of this antenna:

Resonances are 7, 14.1, 21.2, 28. I have enough scrap aluminum that I am going to build this antenna later this summer. Of course there are many dipole variants of this design. I think I have figured a way to add 80M the WARC bands as well but mostly this needs to be a solid contest antenna on 40, 20, 15, and 10 since these are the point rich bands.

My other choice would be some kind of tri-bander with a 40M dipole on the same feed point. This would be a definite step up in performance. Since the radio has only one TX key line at this point getting all fancy with multiple amps and exotic antenna is probably a waste though you could certainly do that for a specific contest (the 160 test comes to mind). You could set up a freq agile amp/antenna switch on say ant 1 and use the contest vertical on say the transverter input and given your situation that may improve your rate. The main thing is to have a efficient antenna that can hear well on multiple bands. On 160 I could envision a BDV (big damn vertical) on ANT 1 and some kind of RX 4 square or K9AY on the transverter port.

I have trouble with the way the RIT is setup in the radio for the contest situation. It is ergonomically terrible. I have a knob and one button is designated to RIT. RIT is extremely important if you are running with 100 hz filters. Very often a station calls back up or down the band.

Here you see my RX on 7.029 and a station 180 hz down the band. I hit the RIT button on the knob and I can immediately tune my passband onto the station down the band. So far so good. To cancel RIT I have to press the knob button AND mouse over to the RIT drop down and turn off the RIT and reset to zero. That's 4 steps.

What should happen nis when you hit RIT the drop down automatically opens and RIT is turned on you can then tune the RIT. If you click RIT a second time RIT toggles off and on but the offset is retained. If you click the button on the knob RIT turns off, the offset is set to zero, the RIT drop down closes, and normal slice tuning resumes, If you have to go from the knob to the mouse to the keyboard to the knob bla bla bla and back in a contest your hosed as far as rate goes.

A couple of times during the contest if I left the radio for a long period of time the main display would freeze. I would have to completely shut every thing down including the radio, power supply and computer. I was running 2 slices, 2 skimmers, 2 bandmaps on Writelog etc. To start from a cold boot is a lot of steps. I'm not sure exactly what happens but I think it's related to multiple ethernet streams.

I wish there was a way to band follow easily. I had that set up with the F5K but the parts I used were not reliable enough to suit me. To make it work you need a 100% reliable LPT port and I was using u home brew usb device.

I am very happy overall with how the radio performs in the contest scenario. It's not SO2R but its about as close as you can get with a single SCU/receiver. There was absolutely no overload, not even close! The 100hz filters were superb and the ability to tailor the audio in the stereo field is perfect to be able to easily discern 2 stations at once. That part surprised me in how effective it was. After a while listening to 2 streams of CW became second nature and not at all distracting. I think it was this plus the razor sharp filters that made this psychological effect of non-stressed 2 things at once happen.

WriteLog is an incredible logger. It interfaces perfectly with skimmer and SSDR.